<p>It's possible to create custom widget in three possible locations where
  you can display your custom content.</p>
<p>Positions are:</p>
<ul>
  <li><code>left-pane</code>
  </li>
  <li><code>center-pane</code>
  </li>
  <li><code>note-detail-pane</code> - located within <code>center-pane</code>,
    but specific to note (split)</li>
  <li><code>right-pane</code>
  </li>
</ul>